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uBITX Setting for Custmized(Hacked or Modified) LPF's

uBITX Setting for Extneded LPF's

I find it hard to find the right title for this posting.
Extneded LPF's, Hacked LPF, Improved LPF... and more

Anyway, I noticed a couple of months ago that the various ways to improve the Spur of uBITX were discussed by some OM's on how to replace the LPF.

This version is for users who want to modify the LPF, Users who use Stock Hardware do not necessarily have to upgrade this firmware.

1.LPF Structure of Stock Hardware 
The basic LPF of uBITX uses Arduino Nano's 5, 4, and 3 I / O.

[ubitx source code]

[ubitx source code]

Frequency >   21.000Mhz   : TXA Off, TXB Off, TXC Off
Frequency >= 14.000Mhz   : TXA  On, TXB Off, TXC Off
Frequency >=  7.000Mhz    : TXA  On, TXB On, TXC Off
Frequency >=       0Mhz    : TXA  On, TXB On, TXC On

2.Schematic for testing LPF of uBITX

In general, you may only use TXA, TXB, TXC such as stock hardware.
But if you use it in a way that controls one relay per I / O, three I / Os will be insufficient.

If you use I2C LCD or Nextion LCD, there will probably be plenty of extra I / O.
In CEC Firmware Version 1.11, you can use D10, D11, D12, D13 as you want.
You can control High / Low by frequency just by setting in uBITX Manager.
Maybe this could be used to control the external linear.

I connected TXA, TXB, TXC and D10~D13 to the breadboard for testing.
yellow lines is TXA~TXC, white lines is D10~D13.

Below is a picture of TXA, TXB, TXC, D10, D11, D12, and D13 lines in uBITX.

TXA, TXB, TXC, D10, D11, D12, and D13 can be viewed according to the frequency as shown below.

3.LPF Control Test for stock hardware





4.Customized LPF (Hacked LPF or Extended LPF)
You will find several ways to modify the LPF to improve uBITX.

- How to use 4 bands (LPF) using 3 relays like uBITX's basic
  (use 3 I/O)

- How to use 4-band to 7-band (LPF) with a combination of relays
  (use 2~3 I/O)

- How to use up to 8 bands (LPF) using Line Decoder such as 74LS138
  (use 3 I/O)

- Various other methods
  (use 3~7 I/O)

5.Compiling source code for using Customized LPF
First of all, the CEC Version allows customized LPF Filter to be configured as desired by the user.

To use your LPF, you need to change the compile options to compile.
I will not provide a precompiled HEX file using this option (To prevent misuse of genuine hardware users)
If you have trouble compiling, please contact me and I will compile it in the form you want.

Uncomment the line below in the ubitx.h file


When you compile with this option enabled, you may get the following error:
(Version 1.11 will only display the following message when using Nextion LCD or 16x02 Dual LCD)

If you see this message, you can remove one feature that you do not use.

If Nextion LCD is used, IF_Shift, ATT, CW Speed etc are all controlled on the LCD.
(If you do not use Text Mode frequently on Nextion LCD, you can make about 20% program space)

The following is a successful compilation after removing the IF_SHIFT function.

See Link below for more details on this.

6.Setting for Customized LPF Users
6.1 Before uploading any settings after uploading the firmware

As you can see in the picture above, the LPF does not do anything.

6.2 LPF structure similar to LPF installed in stock uBITX

As you can see in the pictures below, it works the same as before firmware update.

6.3 Relay Combination or Decode (such as 74LS138)
7 LPFs are available.
The frequency range can be set as desired by the user.









6.4 D10 ~ D13 Extended Mode
This mode is only available for I2C LCD (16x02, 20x04) or Nextion LCD (TJC LCD) users.







6.5 Clone mode using D10~D12 (for External Power Amplifier)
Perhaps this function can be applied not only to LPF but also to various applications.

This is done by running in Clone mode.







Source code and uBITX Manager can be downloaded from the link below.
Download File :


  1. By mistake of mine, I made the mistake of connecting the digital and analog cables backwards.
    The screen is illuminated white.
    Could you tell me if only the firmware was corrupted or maybe some component failed?
    Thank you

  2. If you need more space and dont want to loose any features you can try this.


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How to upgrade uBITX Firmware

uBITX is based on Arduino Nano. So uBITX's firmware upgrade method is the same as Arduino.
There are two ways to upgrade the firmware of uBITX.

The first is to compile the source from the Arduino IDE, and the second is to upload the compiled hex file using the Firmware Upgrade Tool.

I'll show you how to upload a compiled hex file as a second method.

1.Connect the uBITX's USB cable to the computer.

2.Run Device Manager on your computer.
  The way to open the Device Manager for each OS Version differs slightly.
  In most Windows, you can easily launch the Device Manager by running.

  On your computer, press the Windows key + R.

 Type devmgmt.msc and press OK Button.

On most operating systems, there will be a serial port named Ports with CH340. If so, the next step is skipped.

If the serial port is not installed as below, you need to install the driver.

Included in uBITX is the Adonano, which uses the CH340 USB To UART part.

Download the latest CH340 driver from the Internet.